Liquid Piston

Old Tech vs New Tech, I have been searching for a good motor generator combination. The time frame for equivalence between electrical energy storage and liquid energy storage is probably greater than 10 years.
Still, electrically driven automobiles, especially with in wheel motors, have many advantages. The disadvantages are range, charge time, and reliability. How do we get close to the parameters of our daily drive given today's technology?
The picture compares two diesel motors of 40hp. The little one besides being smaller and lighter is also less complicated and more efficient. Running a motor like this at constant velocity increases both reliability and efficiency. Is this kind of range extender enough to compete with gasoline guzzling SUV's which most of us can no longer afford to drive. The factors inhibiting the adoption of efficient personal transportation come from both the consumer and automobile ecosystem stakeholders. Consumer resistance is waning. Mass media can make today's alternatives into desirable options. Vested interests are actively trying to prevent this. Despite this companies producing a "liquid piston" have a limited time span in which to recoup there initial investment. The Chinese purchased Protean Electric, will this be there next acquisition?
Moving proactively into electric mobility will allow for mass manufacturing of all the other components to achieve efficiencies of scale for when the power-source becomes available.
A gallon of gasoline (roughly 4.5 liters) weighs approximately 6 pounds (less than 3 kilos), occupies a mere 230 cubic inches but contains the equivalent of 36 kWhs of electrical energy. For better or worse, this is the energy density standard to which the driving public has gotten accustomed over the years. Anything heavier, bulkier or with less energy density would be considered inferior, hence the main obstacle to popularity of PEVs.